On Tue, Jun 21, 2022 at 11:03 PM H.J. Lu via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> When memchr is applied on a constant string of no more than the bytes of
> a word, inline memchr by checking each byte in the constant string.
>
> int f (int a)
> {
> return __builtin_memchr ("eE", a, 2) != 0;
> }
>
> is simplified to
>
> int f (int a)
> {
> return (char) a == 'e' || (char) a == 'E';
> }
>
> gcc/
>
> PR tree-optimization/103798
> * match.pd (__builtin_memchr (const_str, a, N)): Inline memchr
> with constant strings of no more than the bytes of a word.
Please do this in strlenopt or so, with match.pd you will end up moving
the memchr loads across possible aliasing stores to the point of the
comparison.
Richard.
> gcc/testsuite/
>
> PR tree-optimization/103798
> * c-c++-common/pr103798-1.c: New test.
> * c-c++-common/pr103798-2.c: Likewise.
> * c-c++-common/pr103798-3.c: Likewise.
> * c-c++-common/pr103798-4.c: Likewise.
> * c-c++-common/pr103798-5.c: Likewise.
> * c-c++-common/pr103798-6.c: Likewise.
> * c-c++-common/pr103798-7.c: Likewise.
> * c-c++-common/pr103798-8.c: Likewise.
> ---
> gcc/match.pd | 136 ++++++++++++++++++++++++
> gcc/testsuite/c-c++-common/pr103798-1.c | 28 +++++
> gcc/testsuite/c-c++-common/pr103798-2.c | 30 ++++++
> gcc/testsuite/c-c++-common/pr103798-3.c | 28 +++++
> gcc/testsuite/c-c++-common/pr103798-4.c | 28 +++++
> gcc/testsuite/c-c++-common/pr103798-5.c | 26 +++++
> gcc/testsuite/c-c++-common/pr103798-6.c | 27 +++++
> gcc/testsuite/c-c++-common/pr103798-7.c | 27 +++++
> gcc/testsuite/c-c++-common/pr103798-8.c | 27 +++++
> 9 files changed, 357 insertions(+)
> create mode 100644 gcc/testsuite/c-c++-common/pr103798-1.c
> create mode 100644 gcc/testsuite/c-c++-common/pr103798-2.c
> create mode 100644 gcc/testsuite/c-c++-common/pr103798-3.c
> create mode 100644 gcc/testsuite/c-c++-common/pr103798-4.c
> create mode 100644 gcc/testsuite/c-c++-common/pr103798-5.c
> create mode 100644 gcc/testsuite/c-c++-common/pr103798-6.c
> create mode 100644 gcc/testsuite/c-c++-common/pr103798-7.c
> create mode 100644 gcc/testsuite/c-c++-common/pr103798-8.c
>
> diff --git a/gcc/match.pd b/gcc/match.pd
> index a63b649841b..aa4766749af 100644
> --- a/gcc/match.pd
> +++ b/gcc/match.pd
> @@ -7976,3 +7976,139 @@ and,
> (match (bitwise_induction_p @0 @2 @3)
> (bit_not
> (nop_convert1? (bit_xor@0 (convert2? (lshift integer_onep@1 @2)) @3))))
> +
> +#if GIMPLE
> +/* __builtin_memchr (const_str, a, N) != 0 ->
> + a == const_str[0] .. || a == const_str[N-1]
> + __builtin_memchr (const_str, a, N) == 0 ->
> + a != const_str[0] .. && a != const_str[N-1]
> + where N is less than the string size. */
> +(for cmp (eq ne)
> + icmp (ne eq)
> + bit_op (bit_and bit_ior)
> + (simplify (cmp:c @0 (BUILT_IN_MEMCHR ADDR_EXPR@1 @2 INTEGER_CST@3))
> + (if (UNITS_PER_WORD <= 8
> + && CHAR_TYPE_SIZE == 8
> + && BITS_PER_UNIT == 8
> + && CHAR_BIT == 8
> + && integer_zerop (@0)
> + && !integer_zerop (@3)
> + && TREE_CODE (TREE_OPERAND (@1, 0)) == STRING_CST
> + && TREE_STRING_LENGTH (TREE_OPERAND (@1, 0)) >= 2
> + && wi::leu_p (wi::to_wide (@3), UNITS_PER_WORD)
> + && wi::ltu_p (wi::to_wide (@3),
> + TREE_STRING_LENGTH (TREE_OPERAND (@1, 0))))
> + (with
> + {
> + const char *p = TREE_STRING_POINTER (TREE_OPERAND (@1, 0));
> + unsigned HOST_WIDE_INT size = TREE_INT_CST_LOW (@3);
> + }
> + (switch
> + (if (size == 1)
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[0]); }))
> + (if (size == 2)
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[0]); })
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[1]); })))
> + (if (size == 3)
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[0]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[1]); })
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[2]); }))))
> + (if (size == 4)
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[0]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[1]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[2]); })
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[3]); })))))
> + (if (size == 5)
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[0]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[1]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[2]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[3]); })
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[4]); }))))))
> + (if (size == 6)
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[0]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[1]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[2]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[3]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[4]); })
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[5]); })))))))
> + (if (size == 7)
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[0]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[1]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[2]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[3]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[4]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[5]); })
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[6]); }))))))))
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[0]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[1]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[2]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[3]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[4]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[5]); })
> + (bit_op
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[6]); })
> + (icmp (convert:char_type_node @2)
> + { build_int_cst (char_type_node, p[7]); })))))))))))))
> +#endif
> diff --git a/gcc/testsuite/c-c++-common/pr103798-1.c
> b/gcc/testsuite/c-c++-common/pr103798-1.c
> new file mode 100644
> index 00000000000..cd3edf569fc
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/pr103798-1.c
> @@ -0,0 +1,28 @@
> +/* { dg-do run } */
> +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> +
> +__attribute__ ((weak))
> +int
> +f (char a)
> +{
> + return __builtin_memchr ("a", a, 1) == 0;
> +}
> +
> +__attribute__ ((weak))
> +int
> +g (char a)
> +{
> + return a != 'a';
> +}
> +
> +int
> +main ()
> +{
> + for (int i = 0; i < 255; i++)
> + if (f (i) != g (i))
> + __builtin_abort ();
> +
> + return 0;
> +}
> +
> +/* { dg-final { scan-assembler-not "memchr" } } */
> diff --git a/gcc/testsuite/c-c++-common/pr103798-2.c
> b/gcc/testsuite/c-c++-common/pr103798-2.c
> new file mode 100644
> index 00000000000..e7e99c3679e
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/pr103798-2.c
> @@ -0,0 +1,30 @@
> +/* { dg-do run } */
> +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> +
> +#include <string.h>
> +
> +__attribute__ ((weak))
> +int
> +f (int a)
> +{
> + return memchr ("aE", a, 2) != NULL;
> +}
> +
> +__attribute__ ((weak))
> +int
> +g (char a)
> +{
> + return a == 'a' || a == 'E';
> +}
> +
> +int
> +main ()
> +{
> + for (int i = 0; i < 255; i++)
> + if (f (i + 256) != g (i + 256))
> + __builtin_abort ();
> +
> + return 0;
> +}
> +
> +/* { dg-final { scan-assembler-not "memchr" } } */
> diff --git a/gcc/testsuite/c-c++-common/pr103798-3.c
> b/gcc/testsuite/c-c++-common/pr103798-3.c
> new file mode 100644
> index 00000000000..ddcedc7e238
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/pr103798-3.c
> @@ -0,0 +1,28 @@
> +/* { dg-do run } */
> +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> +
> +__attribute__ ((weak))
> +int
> +f (char a)
> +{
> + return __builtin_memchr ("aEgZ", a, 3) == 0;
> +}
> +
> +__attribute__ ((weak))
> +int
> +g (char a)
> +{
> + return a != 'a' && a != 'E' && a != 'g';
> +}
> +
> +int
> +main ()
> +{
> + for (int i = 0; i < 255; i++)
> + if (f (i) != g (i))
> + __builtin_abort ();
> +
> + return 0;
> +}
> +
> +/* { dg-final { scan-assembler-not "memchr" } } */
> diff --git a/gcc/testsuite/c-c++-common/pr103798-4.c
> b/gcc/testsuite/c-c++-common/pr103798-4.c
> new file mode 100644
> index 00000000000..00e8302a833
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/pr103798-4.c
> @@ -0,0 +1,28 @@
> +/* { dg-do run } */
> +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> +
> +__attribute__ ((weak))
> +int
> +f (char a)
> +{
> + return __builtin_memchr ("aEgi", a, 4) != 0;
> +}
> +
> +__attribute__ ((weak))
> +int
> +g (char a)
> +{
> + return a == 'a' || a == 'E' || a == 'g' || a == 'i';
> +}
> +
> +int
> +main ()
> +{
> + for (int i = 0; i < 255; i++)
> + if (f (i) != g (i))
> + __builtin_abort ();
> +
> + return 0;
> +}
> +
> +/* { dg-final { scan-assembler-not "memchr" } } */
> diff --git a/gcc/testsuite/c-c++-common/pr103798-5.c
> b/gcc/testsuite/c-c++-common/pr103798-5.c
> new file mode 100644
> index 00000000000..0d6487a13df
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/pr103798-5.c
> @@ -0,0 +1,26 @@
> +/* { dg-do run { target int128 } } */
> +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> +
> +__attribute__ ((weak))
> +int f(char a)
> +{
> + return __builtin_memchr ("aEgiH", a, 5) == 0;
> +}
> +
> +__attribute__ ((weak))
> +int g(char a)
> +{
> + return a != 'a' && a != 'E' && a != 'g' && a != 'i' && a != 'H';
> +}
> +
> +int
> +main ()
> +{
> + for (int i = 0; i < 255; i++)
> + if (f (i) != g (i))
> + __builtin_abort ();
> +
> + return 0;
> +}
> +
> +/* { dg-final { scan-assembler-not "memchr" } } */
> diff --git a/gcc/testsuite/c-c++-common/pr103798-6.c
> b/gcc/testsuite/c-c++-common/pr103798-6.c
> new file mode 100644
> index 00000000000..5ccb5ee66e0
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/pr103798-6.c
> @@ -0,0 +1,27 @@
> +/* { dg-do run { target int128 } } */
> +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> +
> +__attribute__ ((weak))
> +int f(char a)
> +{
> + return __builtin_memchr ("aEgiHx", a, 6) != 0;
> +}
> +
> +__attribute__ ((weak))
> +int g(char a)
> +{
> + return (a == 'a' || a == 'E' || a == 'g' || a == 'i' || a == 'H'
> + || a == 'x');
> +}
> +
> +int
> +main ()
> +{
> + for (int i = 0; i < 255; i++)
> + if (f (i) != g (i))
> + __builtin_abort ();
> +
> + return 0;
> +}
> +
> +/* { dg-final { scan-assembler-not "memchr" } } */
> diff --git a/gcc/testsuite/c-c++-common/pr103798-7.c
> b/gcc/testsuite/c-c++-common/pr103798-7.c
> new file mode 100644
> index 00000000000..40fd38257d1
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/pr103798-7.c
> @@ -0,0 +1,27 @@
> +/* { dg-do run { target int128 } } */
> +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> +
> +__attribute__ ((weak))
> +int f(char a)
> +{
> + return __builtin_memchr ("aEgiHjZ", a, 7) == 0;
> +}
> +
> +__attribute__ ((weak))
> +int g(char a)
> +{
> + return (a != 'a' && a != 'E' && a != 'g' && a != 'i' && a != 'H'
> + && a != 'j' && a != 'Z');
> +}
> +
> +int
> +main ()
> +{
> + for (int i = 0; i < 255; i++)
> + if (f (i) != g (i))
> + __builtin_abort ();
> +
> + return 0;
> +}
> +
> +/* { dg-final { scan-assembler-not "memchr" } } */
> diff --git a/gcc/testsuite/c-c++-common/pr103798-8.c
> b/gcc/testsuite/c-c++-common/pr103798-8.c
> new file mode 100644
> index 00000000000..0841b18cea4
> --- /dev/null
> +++ b/gcc/testsuite/c-c++-common/pr103798-8.c
> @@ -0,0 +1,27 @@
> +/* { dg-do run { target int128 } } */
> +/* { dg-options "-O2 -fdump-tree-optimized -save-temps" } */
> +
> +__attribute__ ((weak))
> +int f(int a)
> +{
> + return __builtin_memchr ("aEgiHx19ABC", a, 8) != 0;
> +}
> +
> +__attribute__ ((weak))
> +int g(char a)
> +{
> + return (a == 'a' || a == 'E' || a == 'g' || a == 'i' || a == 'H'
> + || a == 'x' || a == '1' || a == '9');
> +}
> +
> +int
> +main ()
> +{
> + for (int i = 0; i < 255; i++)
> + if (f (i + 256) != g (i + 256))
> + __builtin_abort ();
> +
> + return 0;
> +}
> +
> +/* { dg-final { scan-assembler-not "memchr" } } */
> --
> 2.36.1
>
